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[GunJack]

Guys,

by chance, over the weekend, I observed first-hand the effects of MW radio transmitters on ADSL signals. I live about 2 miles from the Radio Wales transmitter in Wrexham, broadcasting on 657kHz. This leaves me with a gap in bitloading at said frequency, with a tail-off either side of the centre.

However, I rebooted on Sunday morning, with no loss of bitloading and an extra .5 Meg downstream sync. Tuning a radio in showed a distinct loss of radio wales, and this lasted until the broadcast was restored, when I lost bits and had to reboot for the sake of stability

So, there you go, MW radio is evil, and should be banned, or at least moved higher up the spectrum 

[roseway]

A little OTT perhaps.   There are still a lot of people who rely on MW radio, and it would be an expensive and troublesome exercise to change all the transmitter frequencies.

[GunJack]

It was a little toungue-in-cheek Eric.......I have to resort to radio 5 if there's nowt on R4

[roseway]

Ah yes, I didn't think you really meant it. Your observation is interesting though, that one strong MW transmitter can have such a significant effect on the overall performance.

[geep]

Cheers,
Peter
PS - During my annual visit to Wrexham I make a point of visiting the chip shop across the road from the big Tesco. Excellent fish 'n chips.

[GunJack]

geep - yes, Jones' chippy is by far the best and has been for years ... locally known as "the cheap chippy", their fish is the best ever 

[jeffbb]

Hi
quote Although, agreed, the published documentation (on TBB) is a little vague on exactly how ADSL2+ can achieve a higher data rate on mid-range lines

quote from Kitz :A minimum of 2 bits per bin is needed for the tone to be usable for ADSL1 (6dB)
ADSL2 and ADSL 2+ support single bit tones (3dB).

Read more: http://www.kitz.co.uk/adsl/adsl_technology.htm#ixzz1PvmQ9Cw6

There is one of the reasons that you can get higher synch rates each single data bit available is worth 4bps .
Regards Jeff

[razpag]

Guys,

by chance, over the weekend, I observed first-hand the effects of MW radio transmitters on ADSL signals. I live about 2 miles from the Radio Wales transmitter in Wrexham, broadcasting on 657kHz. This leaves me with a gap in bitloading at said frequency, with a tail-off either side of the centre.

However, I rebooted on Sunday morning, with no loss of bitloading and an extra .5 Meg downstream sync. Tuning a radio in showed a distinct loss of radio wales, and this lasted until the broadcast was restored, when I lost bits and had to reboot for the sake of stability

So, there you go, MW radio is evil, and should be banned, or at least moved higher up the spectrum 

Openreach will fit an RF3 filter to try and overcome nuisance frequencies if requested. I've been told, but can't fully confirm, that the NTE2000 (BT's own model) also has some sort of mini-choke incorporated within it, which again apparently screens out some nuisance frequencies. As I'm not an expert on this yet ( regarding another thread about REIN), this is just my thoughts and opinions Gun Jack. No harm in asking OR to fit an RF3 Filter though.

[roseway]

The RF3 filter won't filter medium wave radio frequencies which fall within the ADSL spectrum. That would be pointless even if it were possible, because it would remove the ADSL bins at those frequencies as well.

[razpag]

Now I'm learning !!! What is it's purpose for please Eric ?? Other frequencies/Bands

[roseway]

I believe that the RF3 filters out the frequencies below the ADSL range, whereas the RF2 filters out the ADSL frequencies (so is a complete no-no for an ADSL setup).

[razpag]

Why are we tasked to fit RF3's if they only remedy frequencies outside ADSL then If the said frequencies are outside the DSL spectrum, would they have any kind of effect on bit-loading etc etc Only asking by the way as I genuinely have no idea.

[GunJack]

Well, typical speech range is ITRO 300Hz - 3kHz, audible frequency is up to 18-20kHz, and the upstream frequencies for ADSL start around 34kHz.

So the RF3 could well be to ensure separation between the upper audible frequencies and the upstream ADSL frequencies. A total band-stop filter from, say, 10kHz to 30kHz would not impact much on the phone frequencies which would generally be lower than 10kHz, but would reduce the harmonic interference from those frequencies (10-30kHz) onto the ADSL signals (3rd harmonic of 30kHz is 90kHz, slap-bang in the middle of where most people get their highest bits-per-tone on ADSL

Sorry if this seems rambling, but I'm bleeding !! (don't ask, accident with a razor   )

[roseway]

I think Gunjack has got it about right. If you think about it, the RF3 is fitted in series with the telephone line, so if it blocked ADSL frequencies it would stop the ADSL from working.

[burakkucat]

RP,

Could you access an OR internal database and make a note of the circuit diagrams of an RF2 and RF3, please? Then provide details of the component values here and someone -- a Radio Amateur, perhaps -- will be able to calculate what frequencies are passed or blocked.

(I wonder what an RF1 filtered/passed/blocked? I'm sure one probably did exist, at some time.)